Concept for making goal decisions by means of magnetic fields

ABSTRACT

A method for deciding whether a movable object has been brought through a goal having a goal area defined by the goal, an internal magnetic field being measurable, within the goal area or in parallel with the goal area, which is larger than an external magnetic field present outside the goal area, the method including a step of generating the internal magnetic field within the goal, a step of providing information about a magnetic field experienced by the movable object, and a step of evaluating the information about the magnetic field to provide a goal statement by means of a detection that the movable object has passed through the internal magnetic field.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. patent application Ser. No.11/555,205, filed on Oct. 31, 2006 which claims priority to Germanpatent application Serial Number 102006047376.0, filed on October 6,2006, each of which are herein incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a concept for making goal decisions bymeans of magnetic fields as may be employed, for example, in footballfor making goal decisions.

2. Description of Prior Art

For quite some time, various interest groups have wished to study andunderstand the sequence of movements of moving objects and/or persons,which requires an exact indication of the object's position in space andtime. What is of particular interest here are, among other things, gameballs, in particular in commercialized types of sport, such asfootballs, or soccer balls, which are highly accelerated inthree-dimensional space, as well as tennis or golf balls. The questionof who was the last to touch the object of the game, how it was hit andwhether it crossed a goal line further may be decisive for the outcomeof the game, depending on the type of game.

Game devices that are used in high-performance sports, such as tennisballs, golf balls, footballs and the like, nowadays can be acceleratedto extremely high speeds, so that the detection of the object during themovement requires highly sophisticated technology. The technical meansemployed so far—mainly cameras—either completely fail to meet therequirements set forth above, or meet them only to an insufficientdegree; also the methods, hitherto known, for position finding by meansof various transmitter and receiver combinations still leave a largeerror margin with regard to the spatial resolution of the positionindication, with regard to the ease of use of the transmitter/receivercomponents required, and above all with regard to evaluating the dataobtained by means of the transmitter/receiver system, so that it is notyet possible, or at least requires a large amount of effort, to evaluatethe results obtained from this data as fast as possible.

It is not only in the field of commercial sports, where movable gamedevices may be employed, but it is also in the personal field that usershave become more and more used to electronic devices indicating variouspieces of information to give a user feedback as to how he/she hasaffected an object, or to provide him/her with information about where agame device is currently situated, for example.

A multiplicity of tasks, such as making goal decisions in a footballmatch, presuppose knowledge of the position and/or orientation of amovable object, such as a ball. In football matches, the question ofwhether or not the ball has exceeded the goal line is, in criticalsituations, one of the most controversial topics. To this end, it isnecessary that the position of the ball can be measured at the goal linewithin an accuracy range of about +/−1.5 cm. In addition, any influenceexerted by persons who are moving close to the ball and/or cover theball, must not play any part in this.

There are numerous methods by means of which a referee's goal decisionmay be reconstructed. These methods are based, for example, ontwo-dimensional or three-dimensional optical sensors having anevaluation system, on exploiting the known radar principle, or on aprinciple of radio localization.

Evaluating video recordings, for example with goal cameras, generallyrequires a lot of effort, and a two-dimensionality of the image planesystems often yields distorted values.

With the principle of radio localization, a movable object, or the ball,is localized by means of electromagnetic wave propagation. For example,a receiver and/or transmitter is integrated into or attached to the ballwhich, upon request, may send data to a central transmitting/receivingdevice. The position of the ball may then be calculated, for example,from signal delay times and/or from differences between signals receivedat at least two different antennas. A disadvantage of radio localizationconsists, for example, in a shadowing and/or in a reflection ofelectromagnetic waves by certain obstacles, such as persons. For thisreason, systems which are based on radio localization do not achieve thelevel of accuracy required for making a goal decision in football. Ashas already been described, current localization methods are based, forexample, on optical sensors having an evaluation system (videoevaluation system), or they are based on the use of RF transponderswithin and outside the movable object, or the ball. Such localizationmethods for making goal decisions entail high investment and maintenancecost, sensitivity toward environmental conditions and a large outlay interms of adapting the evaluation algorithms. For close-rangelocalization, i.e. position determination regarding an object within asmall area, systems using radio localization are not suitable, sincewith a small geometrical expansion, differences of various signal delaytimes are hardly measurable any more. Thus, the requirements placed uponsystems for localizing a movable object are not met, or are met only toan insufficient degree, by this method with regard to economy,robustness, clock time and object independence, for accurate positiondetermination for making goal decisions, for example within a range of afew centimeters.

SUMMARY OF THE INVENTION

It is thus the object of the present invention to provide an improvedconcept for making goal decisions.

In accordance with a first aspect, the invention provides a device forgenerating a magnetic field within a goal having a bounded goal areawhich is defined by the goal, and through which a movable object must bebrought so as to achieve a goal, the device being configured togenerate, within the goal area or in parallel with the goal area, aninternal magnetic field larger than an external magnetic field presentoutside the goal area.

In accordance with a second aspect, the invention provides a device fordetermining whether a movable object has been brought through a goalhaving a goal area defined by the goal, an internal magnetic field beingmeasurable within the goal area or in parallel with the goal area, theinternal magnetic field being larger than an external magnetic fieldextending outside the goal area, the device including:

-   -   a provider for providing information about a magnetic field        experienced by the movable object; and    -   an evaluator for evaluating the information about the magnetic        field so as to provide a goal statement, the evaluator being        configured to detect that the movable object has passed through        the internal magnetic field.

In accordance with a third aspect, the invention provides a method forgenerating a magnetic field within a goal having a bounded goal areawhich is defined by the goal and through which a movable object is to bebrought to achieve a goal, including a step of generating an internalmagnetic field larger than an external magnetic field present outsidethe goal area.

In accordance with a fourth aspect, the invention provides a method ofdetermining whether a movable object has been brought through a goalhaving a goal area defined by the goal, an internal magnetic field beingmeasurable, within the goal area or in parallel with the goal area,which is larger than an external magnetic field present outside the goalarea, the method including the steps of:

-   -   providing information about a magnetic field experienced by the        movable object; and    -   evaluating the information about the magnetic field to provide a        goal statement by means of a detection that the movable object        has passed through the internal magnetic field.

In accordance with a fifth aspect, the invention provides a method fordeciding whether a movable object has been brought through a goal havinga goal area defined by the goal, an internal magnetic field beingmeasurable, within the goal area or in parallel with the goal area,which is larger than an external magnetic field present outside the goalarea, the method including the steps of:

-   -   generating the internal magnetic field within the goal;    -   providing information about a magnetic field experienced by the        movable object; and    -   evaluating the information about the magnetic field to provide a        goal statement by means of a detection that the movable object        has passed through the internal magnetic field.

In accordance with a sixth aspect, the invention provides a computerprogram having a program code for performing the method for generating amagnetic field within a goal having a bounded goal area which is definedby the goal and through which a movable object is to be brought toachieve a goal, including a step of generating an internal magneticfield larger than an external magnetic field present outside the goalarea,

-   -   when the computer program runs on a computer or a        microcontroller.

In accordance with a seventh aspect, the invention provides a computerprogram having a program code for performing the method of determiningwhether a movable object has been brought through a goal having a goalarea defined by the goal, an internal magnetic field being measurable,within the goal area or in parallel with the goal area, which is largerthan an external magnetic field present outside the goal area, themethod including the steps of:

-   -   providing information about a magnetic field experienced by the        movable object; and    -   evaluating the information about the magnetic field to provide a        goal statement by means of a detection that the movable object        has passed through the internal magnetic field,        when the computer program runs on a computer or a        microcontroller.

In accordance with a eighth aspect, the invention provides a computerprogram having a program code for performing the method for decidingwhether a movable object has been brought through a goal having a goalarea defined by the goal, an internal magnetic field being measurable,within the goal area or in parallel with the goal area, which is largerthan an external magnetic field present outside the goal area, themethod including the steps of:

-   -   generating the internal magnetic field within the goal;    -   providing information about a magnetic field experienced by the        movable object; and    -   evaluating the information about the magnetic field to provide a        goal statement by means of a detection that the movable object        has passed through the internal magnetic field,        when the computer program runs on a computer or a        microcontroller.

The findings of the present invention are that a goal decision may bemade in that a game device, or a ball, misses, in the vicinity of thegoal, by means of a magnetic field sensor, a static magnetic fieldgenerated by a U-shaped or horseshoe-shaped magnet, which is adjusted tothe geometric shape of the goal, in the goal area or in parallel withthe goal area. The magnetic field, or internal magnetic field, generatedwithin the goal area or in parallel with the goal area is larger than anexternal magnetic field prevailing outside the goal area (e.g. theearth's magnetic field). By means of the measured intensity of theinternal magnetic field which, in accordance with an embodiment of thepresent invention, has its maximum magnitude within the goal plane, orgoal area, a decision may be made as to whether or not a movable object,or a ball, has exceeded the goal line.

For this purpose, in accordance with an embodiment of the presentinvention, a goal exhibits hollow side posts and a hollow crossbar, eachhaving ferromagnetic cores arranged therein. The ferromagnetic cores arepreferably arranged in a continuous manner within the side posts andwithin the crossbar. At least one of the ferromagnetic cores has a coilwound around it, which may be supplied with current for generating thestatic internal magnetic field. If the coil is supplied with current, amagnetic field which is at least approximately homogenous will formwithin the goal area. The magnetic field will be similar to that of ahorseshoe magnet. If a ball which, in accordance with an embodiment ofthe present invention, is provided with a three-dimensional magneticfield sensor is brought through the goal area bounded by the side postsand the crossbar, the magnetic field sensor of the ball will measure amaximum of the magnetic field intensity when the goal line is crossed.At the time the maximum of the magnetic field is measured, the ball willbe positioned, for example, precisely in the plane bounded by the goalline and the goal.

If, in accordance with an embodiment of the present invention, themagnetic field is generated such that its maximum magnitude ispositioned precisely within the plane bounded by the goal and the goalline, a further additional condition will be required for an unambiguousgoal decision, in accordance with an embodiment of the presentinvention. In accordance with an embodiment of the present invention,this additional condition is a direction of motion of the ball. Byexploiting the Doppler effect, a determination is made as to whether aball is moving away from the pitch into the goal, or away from the goaltoward the pitch. For this purpose, in accordance with an embodiment ofthe present invention, the ball comprises a radio transmitter, so thatfrequency shifts of a carrier signal may be measured on the grounds ofthe Doppler effect.

In accordance with a further embodiment of the present invention, themagnetic field and/or the internal magnetic field is generated inparallel with the goal area behind the goal line. This may be achieved,in accordance with an embodiment of the present invention, in that,e.g., only the rear of the goal, i.e. the rear of the side posts and ofthe crossbar, is coated with a ferromagnetic material. This results in adissymmetry in the field distribution with regard to the goal line. Thismeans that the maximum magnitude of the magnetic field is not formed on,but behind the goal line. This dissymmetry may be exploited, inaccordance with the invention, to make an unambiguous goal decision.

An advantage of the present invention is that the system for making goaldecisions need not be calibrated in advance. A goal decision may be madeon the basis of observing a time curve of the magnetic field strengthmeasured in the vicinity of the goal. If, for example, a maximum of themagnetic field strength is detected, a condition sufficient for an eventof a “goal” will thus be at hand.

A further advantage of the present invention is that the inventivesystem is very simple to realize. In accordance with an embodiment ofthe present invention, for example, hollow goal posts and a hollowcrossbar may be provided, to this end, with ferromagnetic cores togenerate, within the goal area, a homogenous static magnetic field bymeans of a coil wound around the ferromagnetic cores. In accordance witha further embodiment of the present invention, a horseshoe-shapedpermanent magnet might be introduced into the goal posts and thecrossbar and/or into an area underneath the goal line so as to achieve a“magnetic field curtain” within the goal area.

Thus, the inventive concept provides the possibility of making goaldecisions on the basis of observing the time curve of a magnetic fieldin the vicinity of a goal.

Thus, embodiments of the present invention have the advantage that agoal decision may be made, for example, without any intervention in theactivity of a ball game.

In addition, the inventive concept for making goal decisions by means ofmagnetic fields is tolerant, e.g., toward persons, i.e. any influenceexerted by persons who are moving in the vicinity of the movable object,or the ball, or who cover the movable object, is irrelevant.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention willbecome clear from the following description taken in conjunction withthe accompanying drawing, in which:

FIG. 1 is a schematic representation of a device for generating amagnetic field within a goal, in accordance with an embodiment of thepresent invention;

FIG. 2 is a schematic front view of a football goal having aferromagnetic material within the goal posts and the crossbar, theferromagnetic material having a coil wound around it, in accordance withan embodiment of the present invention;

FIG. 3 is a schematic curve of the magnetic field strength, generated bythe device in accordance with FIG. 2, within an area around the goalline;

FIG. 4 is a schematic representation of a device for generating amagnetic field in parallel with the goal area in accordance with anembodiment of the present invention;

FIG. 5 is a schematic representation of the magnetic field, generated bythe device in accordance with FIG. 4, within an area around the goalline;

FIG. 6 is a schematic representation of a critical goal decision, a ballhitting the ground once just behind the goal line, and once just beforethe goal line;

FIG. 7 a is a schematic representation of the time curve of a magneticfield in a goal situation depicted in FIG. 6;

FIG. 7 b is a schematic representation of the time curve of a magneticfield in the goal situation depicted in FIG. 6, in accordance with afurther embodiment of the present invention; and

FIG. 8 is a schematic representation of an approach to measuring thespeed of a ball by means of the Doppler effect, in accordance with anembodiment of the present invention;

FIG. 9 is a device for determining whether a movable object has beenbrought through a goal having a goal area defined by the goal, inaccordance with an embodiment of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

With regard to the following description, one should note that in thevarious embodiments, functional elements which are identical or haveidentical actions comprise identical reference numerals, and that thedescriptions of these functional elements are thus interchangeablewithin the various embodiments presented below.

In the following, the expression of “signal” will be used for currentsor voltages alike, unless explicitly indicated otherwise.

FIG. 1 shows a schematic representation of a device 100 for generating amagnetic field within a goal, for example a football goal, having abounded goal area defined by the goal, through which a movable object isto be brought in order to achieve a goal. Device 100 exhibits a firstarea 110 comprising a ferromagnetic material, a second area 120comprising a ferromagnetic material, and a third area 130 comprising aferromagnetic material.

A goal, not shown in FIG. 1, generally has four demarcations. Onedemarcation is embodied by a first side post, a further demarcation isembodied by a second side post, an additional demarcation is defined bya crossbar, and a further demarcation of a goal is given by a goal line.Generally, the first area 110 of device 100 is associated with a firstdemarcation of the goal, the second area 120 of device 100 is associatedwith a second demarcation of the goal, and the third area 130 of device100 is associated with a third demarcation of the goal. Theferromagnetic material may thus be attached, for example, within thegoal demarcations, to the goal demarcations or within a certain distancefrom the goal demarcations.

In accordance with an embodiment of the present invention, the threeareas 110-130 are located within or immediately at three demarcations ofthe goal so as to generate, in a plane defined by the goal area and thegoal line, an at least approximately homogenous magnetic field.

To this end, in accordance with an embodiment of the present invention,device 100 might include a U-shaped or horseshoe-shaped permanentmagnet.

In accordance with a preferred embodiment of the present invention,device 100 comprises a coil associated with the first 110, second 120 orthird areas 130, the coil and the first 110, second 120 and third areas130 being arranged such that closed magnetic field lines result whichhave portions located within the goal area or in parallel with the goalarea, and the remaining portions of which are guided through the first110, second 120 and third areas 130. Thus, the areas are arranged in aU-shaped or horseshoe-shaped manner. In order to be able to vary arange, or strength, of the magnetic field generated using the coil,device 100 further includes, in accordance with an embodiment of thepresent invention, a means for generating coil activation signalsconfigured to generate the coil activation signals with differentintensities, i.e., for example, coil currents of different intensities.

In this respect, FIG. 2 shows an embodiment of the present invention.FIG. 2 shows a front view of a football goal 200 having a first sidepost 200 a, a second side post 200 b, and a crossbar 200 c. Footballgoal 200 is located on a goal line 210. In addition, football goal 200comprises a core 220 having first, second and third areas made offerromagnetic material. In addition, ferromagnetic core 220 has a coil230 wound around it so as to generate, in the plane defined by goal line210 and football goal 200, an at least approximately homogenous internalmagnetic field, the field lines of which are indicated by referencenumeral 240 by way of example.

Goal 200 comprises four demarcations. A first demarcation is formed byfirst side post 200 a, a second demarcation is formed by second sidepost 200 b, and a third demarcation is formed by crossbar 200 c.Finally, a fourth demarcation is defined by goal line 210. Theferromagnetic material within the first demarcation, or first side post200 a, forms the first area 110 of device 100 for generating themagnetic field. The ferromagnetic material within the seconddemarcation, or second post 200 b, of goal 200 forms the second area 120of device 100 for generating the magnetic field. Finally, theferromagnetic material within the crossbar, or the third demarcation, ofgoal 200 forms the third area 130 of the device for generating themagnetic field.

In the embodiment of the present invention which is shown in FIG. 2,coil 230 is associated with third area 130 of device 100, and/or withcrossbar 200 c. If a voltage is applied to the coil, or if a current isapplied to the coil 230, this results in a curve of magnetic field lineslike in a horseshoe magnet, as is indicated by reference numeral 240 inFIG. 2. An at least approximately homogenous field line curve arisesbetween the two side posts 200 a and 200 b. The field lines between thetwo side posts 200 a, 200 b close via ferromagnetic core 220 of goal200. Therefore, virtually no additional magnetic field is generatedoutside goal 200. Therefore, only the earth's weak magnetic field willtypically prevail outside football goal 200. Within the goal area, aninternal magnetic field is generated which superimposes the earth'smagnetic field outside the goal area. If coil 230 is supplied withsufficient current, what results within the goal area is a kind ofmagnetic field curtain which will be penetrated by a movable object, ora ball, if someone scores a goal.

If, for example, a ball has a three-dimensional magnetic field sensor inits interior, this magnetic field sensor will measure a maximummagnitude of the magnetic field strength upon penetrating the magneticfield curtain in the goal area. This connection is to be illustratedbelow with reference to FIG. 3.

FIG. 3 shows a curve 300 of a magnetic field strength |B| in an areaaround the goal area. The |B| axis characterizes the goal area at x=0.The x axis points in the direction of the pitch.

If a ball approaches goal 200 from the sides of the pitch, i.e. in thenegative x direction, a three-dimensional magnetic field sensor mountedwithin the ball will measure a field strength curve shown in FIG. 3 inexemplary terms. Until the goal line, or the goal area, is reached atx=0, the magnetic field strength will continuously increase, and willreach its maximum in the goal area at x=0. Once the goal area, or thegoal line, has been crossed, the magnetic field will decreasecontinuously.

The symmetrical field strength curve shown in FIG. 3 will result whenthe at least approximately homogenous magnetic field is generated ingoal area 310, such as, for example, in the embodiment of the presentinvention which is depicted in FIG. 2.

In accordance with a further embodiment of the present invention, theferromagnetic material could also be located within crossbar 200 c, oneof the two side posts 200 a or 200 b, and in an area below goal line 210which is parallel to crossbar 200 c. The resulting field lines withinthe goal area would not be parallel to crossbar 200 c, but parallel tothe two side posts 200 a, 200 b. Due to the lower height of a footballgoal in comparison with its width, in accordance with this embodiment ofthe present invention, with equal current supply to coil 230, largerfield strengths may be achieved within the goal area than in theembodiment of the present invention depicted in FIG. 2.

Because of the field strength curve, as is depicted in FIG. 3, which issymmetrical around the goal line and/or the goal area, ambiguities mayresult in critical goal situations (e.g. “Wembley goal”) which can onlybe solved if a further additional condition is verified beside the timecurve of the magnetic field strength. This circumstance will be dealtwith below with reference to FIGS. 6-7 b.

Contemplating an additional condition beside the time curve of themagnetic field may be circumvented if a dissymmetric curve of themagnetic field strength is generated with regard to the goal line and/orthe goal area. In accordance with an embodiment of the presentinvention, this may be achieved in that a magnetic field is generatedbehind the goal line in parallel with the goal area by means of aninventive device 100 for generating a magnetic field. On this subject,FIG. 4 shows a schematic perspective representation of a device 100 forgenerating a magnetic field behind the goal line in parallel with thegoal area.

FIG. 4 shows a goal 200 having a first side post 200 a, a second sidepost 200 b, and a cross bar 200 c. Goal 200 is located on a goal line210. Behind goal line 210, a device 100 for generating a magnetic fieldis provided at a distance d. Device 100 comprises a first area 110comprising a ferromagnetic material, a second area 120 comprising aferromagnetic material, and a third area 130 comprising a ferromagneticmaterial. In addition, the device comprises a coil 230 associated withthe third area 130, or wound around third area 130. First area 110 ofdevice 100 is associated with first side post 200 a, second area 120 ofdevice 100 is associated with second side post 200 b of goal 200, andthird area 130 of device 100 is associated with crossbar 200 c of goal200. The dimensions of device 100 are at least as large as thedimensions of football goal 200 so as not to impede, if possible, anoccurrence of a “goal” event.

If a current is applied to coil 230, what results in accordance with anembodiment of the present invention are closed magnetic field lineshaving a portion located/positioned in parallel with the goal area at adistance d behind goal line 210, and the remaining portions of which areguided through the first 110, second 120 and third areas 130 of device100.

In comparison with the arrangement shown in FIG. 2, the embodiment ofthe present invention in accordance with FIG. 4 yields a curve of themagnetic field strength which is dissymmetrical with regard to the goalarea, or the goal line 210. This circumstance is depicted in FIG. 5.

FIG. 5 shows a curve of the magnetic field strength of the magneticfield generated by the arrangement in accordance with FIG. 4. Thehorseshoe magnet formed by device 100 including coil 230 is positioned,at a distance d, behind goal line 210, or crossbar 200 c. If a ballmoves toward goal 200, it will see an increase in the magnetic fieldstrength up to a maximum positioned behind the goal line 210 at thedistance d. Once the maximum of the magnetic field strength has beenreached, the ball has passed the magnetic field curtain, whereupon themagnetic field strength decreases again.

If a magnetic field sensor, preferably a three-dimensional magneticfield sensor, is positioned within the center of the ball, and ifdistance d amounts to, for example, half the ball's diameter, themagnetic field sensor within the ball will detect the maximum of themagnetic field strength precisely at that moment when the ball ispositioned fully behind goal line 210. Thus, as long as no maximum hasbeen detected, it can be assumed that no goal has been scored.

A goal decision by means of the inventive concept will be generallyrequired when a referee cannot make out whether or not a ball ispositioned behind the goal line. Such scenarios are feasible, forexample, when a goalkeeper catches the, ball, however it is not certainwhether the goalkeeper has caught the ball before the goal line. Afurther scenario will result, for example, when a ball bounces off thelower edge of the crossbar and then, within fractions of seconds,touches the ground either just behind or just before the goal line. Incases like these, it is often not possible for a referee to decide, evenwith video recordings, whether or not a goal has been scored.

The latter scenario is schematically depicted in FIG. 6. FIG. 6 shows acrossbar 200 c underneath which goal line 210 is located. The x axisdepicted in FIG. 6 points away from the goal, i.e. in the direction ofthe pitch. In a first scenario, a ball 600 bounces off crossbar 200 c atan angle +α relative to the goal area and touches the ground in thedirection of the pitch, i.e. before goal line 210. In a second scenario,ball 600 bounces off crossbar 200 c in an opposite manner at an angle of−α relative to the goal area, and hits the ground in the goal behindgoal line 210.

If the magnitude of angle α is sufficiently small, it will be virtuallyimpossible to decide with the naked eye during a game whether ball 600hits the ground before or behind goal line 210.

With the inventive concept, however, it is now possible to decidewhether or not ball 600 has crossed goal line 210. In the following, theembodiment of the present invention in accordance with FIG. 4 shall beused as the basis. The magnetic field generated and/or the magneticcurtain generated here is located at a distance d behind goal line 210in parallel with the goal area.

FIG. 7 a shows the curves of the magnetic field strength which resultfor the scenarios depicted in FIG. 6, plotted over time t. The dottedcurve indicated by reference numeral 700 describes the first scenario,wherein the ball is shot, at a high speed v, from the direction of thepitch at crossbar 200 c, bounces off same in an angle of +α in relationto the goal area, and hits the ground before goal line 210. Thus, nogoal is scored in this first scenario. The curve indicated by referencenumeral 710 describes the time curve of the magnetic field strength forthe second scenario, wherein the ball is shot, at a high speed v, atcrossbar 200 c from the direction of the pitch, bounces of off crossbar200 c in a downward direction at an angle of −α relative to the goalarea, and hits the ground behind goal line 210. Thus, in this secondscenario, a goal is scored.

Up to a moment t₀, the two time curves of the magnetic field strengths700 and 710 measured are superimposed in a congruent manner. Up tomoment t₀, the ball approaches crossbar 200 c and, thus, the goal areadefined by crossbar 200 c and goal line 210, from the direction of thepitch. As has already been described above, the ball passes through anarea of increasing magnetic field strength. In both scenarios, ball 600hits crossbar 200 c at moment t₀.

In the first scenario, i.e. that scenario in which no goal is scored,ball 600 bounces off crossbar 200 c, at moment t₀, such that the sign ofthe x component v_(x) of speed v is reversed. Thereby, the ball passesthrough the magnetic field in the reverse direction. Due to the factthat the magnitude |v_(x)| of speed component v_(x) is smaller thanprior to hitting crossbar 200 c, the ball passes through the magneticfield at a lower speed, of course. This circumstance is indicted in FIG.7 a.

In the second scenario, ball 600 bounces off, at moment t₀, fromcrossbar 200 c such that a goal situation results. Due to the ballhitting crossbar 200 c, the magnitude |v_(x)| of speed component v_(x)will indeed change, but the sign of speed component v_(x) will notchange the sign, however, in comparison with the time prior to the ballhitting the crossbar. Due to the maximum of the magnetic field at thedistance d behind the goal line 210, in the second scenario, the ballcontinues to experience, after hitting the crossbar, an increasingmagnetic field as is indicated by curve 710 in FIG. 7 a. Here, too, themagnitude |v_(x)| of speed component v_(x) will decrease due to the ballhitting the crossbar, so that at moment t₀, a point of discontinuity canbe discerned in the inclination d|B|/dt of magnetic field curve 710. Itis only after the ball has reached the maximum of curve 710 that theball has exceeded goal line 210 with its full diameter, and that a“goal” event can be indicated.

With a dissymmetric arrangement of the magnetic field curtain regardingthe goal line, or the goal area, an unambiguous goal decision may thusbe taken. However, it may also occur that such a dissymmetricarrangement of the magnetic field curtain is not possible because, forexample, additional devices behind a goal are not allowed in accordancewith regulations. In such a case, the ferromagnetic areas may bemounted, for example, within the goal demarcations, or the goal posts,the crossbar or an area below the goal line, which, however, will resultin an at least approximately symmetrical field strength curve withregard to the goal line.

If the magnetic field is generated, for example, using an embodiment ofthe present invention which is shown in FIG. 2, i.e. if the maximum ofthe magnetic field is located within the goal area, this will result,for the scenarios discussed with reference to FIG. 6, in the time curvesof the magnetic field strength which are illustrated in FIG. 7 b.

Dotted curve 720 describes the first scenario wherein no goal occurs,continuous curve 730 relates to the second scenario wherein ball 600hits the ground behind goal line 210, and thus a goal event occurs. Inboth scenarios, ball 600 sees an increase in the magnetic field strengthup to a maximum until it hits crossbar 200 c at moment t₀, the maximumexisting within the goal area, i.e. within the area demarcated/definedby goal line 210 and crossbar 200 c. Since in both scenarios, ball 600keeps moving, after the impact at time t₀, at a speed component v_(x)which is the same in terms of magnitude, but different in terms ofsigns, and since the internal magnetic field is configured symmetricallyaround the goal area, the time curve of the magnetic field strength, asmeasured within the ball by a magnetic field sensor, will be virtuallyidentical for both scenarios. Thus, it is not readily possible here tomake a goal decision without drawing on additional condition, theadditional condition differing from the internal magnetic field.

In accordance with an embodiment of the present invention, theadditional condition provides an indication as to the side from whichthe movable object, or ball 600, approaches goal 200 or moves away fromit. In accordance with an embodiment of the present invention, ball 600has a three-dimensional magnetic field sensor and a radio transmitterlocated therein which serves to transmit the field strengths measured toa central evaluation device. In order to be able to make a statement asto whether ball 600 is moving away from or toward goal 200, the Dopplereffect is exploited in accordance with one embodiment of the presentinvention. The change in the frequency of waves of any kind, while asignal source is moving toward or away from an observer is referred toas the Doppler effect. In the event of an approximation, the frequencyincreases, in the opposite case it decreases. If, thus, ball 600transmits a carrier signal having at a frequency f_(c), and if ball 600moves toward goal 200, a receiver located, for example, behind the goalwill see a frequency shift Δf>0 as compared to carrier frequency f_(c).If, on the other hand, the ball moves away from the goal, the receiverlocated behind the goal will see a frequency shift Δf<0 as compared tocarrier frequency f_(c). This connection is schematically presented inFIG. 8.

FIG. 8 depicts a schematic frequency diagram having four spectral lines800, 810, 820, 830. Spectral line 800 at frequency f_(c) signifies, forexample, the carrier frequency of the radio transmitter of ball 600,spectral line 810 at frequency f_(c)+Δf_(D) represents a carrierfrequency of the frequency transmitter of ball 600 which has beenshifted by a mean Doppler frequency shift Δf_(D). Spectral line 820 atfrequency f_(c)+Δf_(D,min) represents a carrier frequency of the radiotransmitter of ball 600 which has been shifted by a minimum Dopplerfrequency shift 66 f_(D,min) and spectral line 830 at frequencyf_(c)+Δf_(D,max) represents a carrier frequency of the radio transmitterof ball 600 which has been shifted by a maximum Doppler frequency shiftΔf_(D,max).

If ball 600 moves toward goal 200, a receiver located behind goal 200will receive a signal shifted in frequency. The magnitude |Δf_(D)| ofthe frequency shift will depend on an angle between a motion vector{right arrow over (ν)} of the ball and the connecting line from thetransmitter and the receiver, i.e. from ball 600 to the receiver. Whenshot, ball 600 will generally exhibit additional rotation. This rotationcauses a periodic oscillation of the frequency received by the receiverby a mean Doppler shift Δf_(D), as is depicted in FIG. 8. Due to therotation, one will obtain an enlarged Doppler spectrum having abandwidth of (Δf_(D,max)+Δf_(D,min)) around a center frequency(f_(c)+Δf_(D)). The symmetry properties of the Doppler spectrum dependon the rotation of the ball. If the mean Doppler frequency Δf_(D) has apositive value, ball 600 is moving toward the receiver and/or towardgoal 200. In the event of a negative value, ball 600 is moving away fromthe receiver and/or goal 200.

If the Doppler frequency, in particular the mean Doppler frequencyΔf_(D), is thus drawn on as an additional condition in addition to thetime curve of the magnetic field strength, it is possible to determine,by means of the Doppler frequency along with the time curve of themagnetic field strength, whether or not a goal has been scored. Theadditional condition is necessary particularly when the curve of themagnetic field strength is symmetrical, i.e. the magnetic field isgenerated, for example, by an inventive device as is shown in FIG. 2.With the inventive device depicted in FIG. 3, the above-describedadditional condition may be dispensed with due to the dissymmetry of themagnetic field curve around the goal line.

FIG. 9 shows a device 900 for determining whether a movable object hasbeen brought through a goal having a goal area defined by the goal.Device 900 comprises a means 910 for providing information about amagnetic field experienced by the movable object. In addition, device900 for determining comprises a means 920 for evaluating the informationabout the magnetic field so as to provide a goal statement. To this end,means 920 for evaluating is coupled to means 910 for providing theinformation about the magnetic field.

Within the goal area or in parallel with the goal area, an internalmagnetic field may be measured which is larger than an external magneticfield present outside the goal area, such as the earth's magnetic field.

In accordance with a preferred embodiment of the present invention,means 910 for providing the information and means 920 for evaluating theinformation are coupled to one another via a radio link. Means 910 forproviding the information about the magnetic field experienced by themovable object is located within the movable object, or the ball. Means910 for providing the information about the magnetic field may comprise,for example, a three-dimensional magnetic field sensor wherein, forexample, a digitalization of the measured values has already beenintegrated onto a sensor chip.

Means 920 for evaluating the information about the magnetic field islocated, in accordance with a preferred embodiment of the presentinvention, in a central evaluating unit coupled, by radio, to themovable object and/or means 910 for providing the information. Means 920for evaluating the information about the magnetic field is configured,in accordance with an embodiment of the present invention, to provide agoal decision by means of the time curve of the magnetic field.

As has already been described above, in accordance with embodiments ofthe present invention, a goal decision may be brought about by detectinga maximum of the temporal magnetic field curve. The conditions for amaximum of the time curve of the magnetic field strength are d|B|/dt=0and d²|B|/dt²<0, it being possible to calculate the magnitude |B| of themagnetic field strength from the components (B_(x), B_(y), B_(z)),measured by the magnetic field sensor, of a magnetic field in a spatialpoint in accordance with |B|=(B_(x) ²+B_(y) ²+B_(z) ²)^(1/2). Thus, thetwo above-mentioned conditions may be verified at any time by means of asequence of magnetic field measured values transmitted by ball 600 andby means of a respective logic.

In accordance with further embodiments of the present invention, onecriterion for making a decision about a goal may also be a change insigns of the first derivation d|B|/dt. When transversing the maximum ofthe magnetic field curve, there will generally be a sign reversal from“+” to “−”, since during an approximation to goal line 210, the magneticfield strength initially increases, and decreases again once goal line210 has been crossed.

In addition, further events may be concluded from the curve of the firstderivation d|B|/dt of the time curve of the magnetic field strength. If,at a specific moment in time, the first derivation exhibits a point ofdiscontinuity, it can be assumed, as described above, that the ball hastouched, for example, a side post or the crossbar. If an internalmagnetic field, as has been described with reference to FIG. 2, isgenerated symmetrically to goal line 210, a means for detecting anadditional condition will also be required, the additional conditiondiffering from the internal magnetic field, and it being possible toevaluate the time curve of the magnetic field and the additionalcondition together. In accordance with an embodiment of the presentinvention, the additional condition will provide an indication as to theside from which the movable object, or the ball, has approached thegoal, or toward which it is moving away from the goal.

The means for detecting the additional condition could thus be, inaccordance with an embodiment of the present invention, a means fordetecting a Doppler frequency shift, in particular a mean Dopplerfrequency shift Δf_(D) mounted, for example, behind a goal.

In accordance with further embodiments of the present invention, forceor motion ratios of the movable object may also be detected so as toobtain an additional condition relating to the time curve of themagnetic field. This may be accomplished, for example, by means ofmotion and/or pressure sensors within the ball, the measurement data ofwhich can be transmitted, via radio transmitter, to a central evaluationmeans.

In accordance with a further embodiment of the present invention, it ispossible to measure the magnetic field, which has been generated bydevice 100 for generating magnetic field, in a three-dimensional mannerat a desired level of accuracy in a location determination area aroundgoal 200 and to associate the measured values and/or the components(B_(x), B_(y), B_(z)) of field vector {right arrow over (B)} for eachrelevant spatial point, for example in a so-called lookup table, withthe respective space coordinates (x, y, z) of the spatial points, and tostore them. Of course, it is just as well feasible for the fieldstrengths and field directions to be calculated, in accordance with afurther embodiment of the present invention, by means of mathematicalformulae in an area of interest within an around the goal so as to besubsequently associated with the respective coordinates (x, y, z) in alookup table. If, subsequently, a field strength and the associatedfield direction are measured at any location of the locationdetermination area around the goal, the measured values may subsequentlybe compared with the values from the lookup table which were measured orcalculated and stored in advance, and thus, a goal decision may possiblybe made.

In accordance with a further embodiment of the present invention, it isfeasible for means 910 for providing the information about the magneticfield and means 920 for evaluating the information about the magneticfield to both be arranged within the movable object, or ball 600. Theinformation about the magnetic field may be stored within the ball, andmay be polled, in accordance with an embodiment of the presentinvention, in a critical goal decision.

The movable object, or ball 600, further requires an energy supply meansfor energy supply purposes. The energy supply may be ensured, forexample, by a battery within ball 600. To ensure a long life of theball's energy supply, it is also possible, for example, to be able toactivate and deactivate same. This should be preferably performed with aview to requiring as few interventions into the game activity aspossible. Ball 600 may be activated, in the vicinity of goal 200, via aweak signal which is sent, for example, from a transmitter, configuredfor this purpose, of a central control/evaluation means. To this end,the ball has, for example, a receiver receiving the activating signaland subsequently activating, via a processor, the measurement systemwithin the ball in the vicinity of goal 200. For example, every 100milliseconds the processor briefly switches on the receiver within theball. As soon as the activating signal is recognized by the ball, theball starts to run in continuous operation.

In addition, the magnetic field generated by an inventive device mayalso be employed as the activating signal. If ball 600 comes close togoal 200, this is recognized by the three-dimensional magnetic fieldsensor within the ball. As soon as this is the case, the measurementsystem within the ball will switch on. Here, too, it is possible tobriefly operate the sensors every 100 milliseconds only.

With the two approaches described above, a detection is only brieflyswitched on to save energy. If ball 600 recognizes no signal over a verylong time, for example one day, a timer for detection is turned up to,for example, ten seconds. Thereby, the energy consumption may again bedrastically reduced. Since, for example, the state of a battery withinthe ball may be polled, it is ensured that a timer within the ball isreset to, for example, 100 milliseconds at the start of the game.

When conductive objects (also persons) are moving within a magneticfield, a magnetic field may be induced within these objects. Thismagnetic field could influence the field geometry of the magnetic fieldgenerated by device 100 for generating a magnetic field. In a footballgame, however, the players do not move fast enough for an observableinduction to be caused. Ball 600, however, may achieve speeds of up to140 km/h. Therefore, in an implementation, care has to be taken,preferably, that the electronic system within ball 600 is as small aspossible and exhibits no large conductive areas.

Any influence on the magnetic field generated by device 100 due to anypower cables located in the vicinity of device 100 is relatively small.A power cable in most cases comprises a conductor and a returnconductor, so that the magnetic fields of the conductor and the returnconductor cancel each other out. Even with single conductors, theinfluence would be relatively small, since with a mains frequency of 50Hz, the field effect would correspond to a slight change in the earth'smagnetic field.

An advantage of the inventive concept for making goal decisions is thefact that a goal decision can occur in a manner which is very robusttoward intentional or unintentional influence. An inventive system formaking goal decisions could be interfered with, for example, in that aradio link between ball 600 and a central computer is interfered with.Since, in accordance with an embodiment of the present invention, areceive antenna is integrated, within a central computing means, closelybehind the goal, interfering with the system requires a lot of effort.In addition, the antenna may be oriented, for example, as a directionalantenna toward the pitch. In addition, a data transmission between ball600 and the central computing means is only active, in accordance withan embodiment of the present invention, when the ball is very close tothe goal, i.e. within the location determination area. A reception powerof the radio link is very high due to the relatively short distancebetween ball 600 and the central computing means. For this reason, apotential attacker would have to use very high-profile equipment, whichthus would be very likely to not be inconspicuous.

The magnetic field generated by device 100 could also be interferedwith. However, artificial magnetic fields do not extend very far intospace. Accordingly, an attacker would have to mount relatively largecoils in order to be able to generate an interference field.

Due to plausibility considerations integrated into evaluation means 920,the system may recognize an interference and, for example, generate awarning if someone should succeed in interfering with the system byradio or via the magnetic field.

Since in the inventive concept for making goal decisions, no radiolocalization is used, other radio systems operating in the samefrequency range will not be disturbed. The directional radio linkbetween ball 600 and a central computer may be located, for example,within the 2.4 GHz range, and it is very narrow-band due to the low datarates to be transmitted., Therefore, it represents no load, for example,for existing WLAN systems (WLAN=wireless local area network).

Since the magnetic field which has been generated and used is within theorder of magnitude of the earth's magnetic field, it may be assumed thatit has no biological effects.

In systems based on radio localization, it is mostly not possible to beable to differentiate, with justifiable effort, signal reflections fromthe original signal if the reflection occurs very close to thetransmitter. These problems do not occur with the inventive approach. Inaddition, no problem exists with regard to a field coverage like withradio localization or optical systems. Magnetic fields may penetratepersons and goal posts in an undamped manner. By means of radio signals,on the other hand, the ball can no longer be located if, for example,there are several persons lying on the ball.

A further advantage of embodiments of the present invention is that themovable object, or the ball, may exhibit low power consumption, since itneed not send a continuous localization signal such as is required, forexample, with radar systems or radio localization systems.

If an inventive system is used, for example, for recognizing goals infootball, extensive installations in a football stadium are notrequired. All necessary installations are only at the two respectivegoals. In addition, there is no need to measure in and/or calibrateantennas or cameras. In addition, there is no unnecessary system loaddue to balls not involved in the game, since they can be switched offand/or are not positioned within reach of the magnetic fields generatedwithin the goal area.

As has already been described above, no intervention into the gameactivity is required with the inventive concept, since activation of theball is performed automatically.

Last but not least, an installation of an inventive system for makinggoal decisions may be performed at considerably reduced cost as comparedwith radio-based or optical systems.

Further uses of the inventive concept are naturally also to be seen inother sports, wherein, for example, critical goal decisions and/or linedecisions are to be made.

It shall be pointed out, in particular, that the inventive scheme mayalso be implemented in software, depending on the circumstances. Theimplementation may be performed on a digital storage medium, inparticular a disk or a CD with electronically readable control signalswhich may cooperate with a programmable computer system and/ormicrocontroller in such a manner that the respective method isperformed. Generally, the invention thus also consists in a computerprogram product having a program code, stored on a machine-readablecarrier, for performing the inventive method when the computer programproduct runs on a computer and/or microcontroller. In other words, theinvention may thus be realized as a computer program having a programcode for performing the method, when the computer program runs on acomputer and/or microcontroller.

While this invention has been described in terms of several preferredembodiments, there are alterations, permutations, and equivalents whichfall within the scope of this invention. It should also be noted thatthere are many alternative ways of implementing the methods andcompositions of the present invention. It is therefore intended that thefollowing appended claims be interpreted as including all suchalterations, permutations, and equivalents as fall within the truespirit and scope of the present invention.

What is claimed is:
 1. A device for generating a magnetic field within a goal having a bounded goal area which is defined by the goal, and through which a movable object must be brought so as to achieve a goal, the device being configured to generate, within the goal area or in parallel with the goal area, an internal magnetic field larger than an external magnetic field present outside the goal area.
 2. The device as claimed in claim 1, the goal having four demarcations, and the device comprising: a first area comprising a ferromagnetic material and being associated with a first demarcation; a second area comprising a ferromagnetic material and being associated with a second demarcation; a third area comprising a ferromagnetic material and being associated with a third demarcation; and a coil associated with the first, second or third areas, the coil and the first, second and third areas being arranged such that closed magnetic field lines result which have portions located within the goal area or in parallel with the goal area, and the remaining portions of which are guided through the first, second and third areas.
 3. The device as claimed in claim 2, the first area corresponding to a first side post, the second area corresponding to a second side post, and the third area corresponding to the crossbar, or the first area corresponding to a side post, the second area corresponding to the crossbar, and the third area corresponding to a goal line on which the goal is located.
 4. The device as claimed in claim 1, wherein the goal comprises hollow side posts and a hollow crossbar, and ferromagnetic cores being arranged within at least one side post and the crossbar.
 5. The device as claimed in claim 1, a rod comprising a ferromagnetic material being buried underneath the goal line.
 6. The device as claimed in claim 1, a ferromagnetic material being deposited on at least one of the side posts and the crossbar.
 7. The device as claimed in claim 1, a ferromagnetic material of the first, second and third areas being arranged in a continuous manner in each case, and the first, second and third areas together forming a U shape.
 8. The device as claimed in claim 1, the first demarcation corresponding to a first side post, the second demarcation corresponding to a second side post, the third demarcation corresponding to the crossbar, and the fourth demarcation corresponding to the goal line, and the first, second and third areas of the device being located in a plane parallel to the goal plane behind the goal line.
 9. The device as claimed in claim 2, the device further comprising a generator for generating coil activation signals.
 10. The device as claimed in claim 9, the generator for generating coil activation signals being configured to generate the coil activation signals with different intensities.
 11. The device as claimed in claim 2, the device including a permanent magnet.
 12. A device for determining whether a movable object has been brought through a goal having a goal area defined by the goal, an internal magnetic field being measurable, within the goal area or in parallel with the goal area, the internal magnetic field being larger than an external magnetic field extending outside the goal area, the device comprising: a provider for providing information about a magnetic field experienced by the movable object; and an evaluator for evaluating the information about the magnetic field so as to provide a goal statement, the evaluator being configured to detect that the movable object has passed through the internal magnetic field.
 13. The device as claimed in claim 12, wherein the provider is configured to provide information about a time curve of the magnetic field, which further comprises a detector for detecting an additional condition, the additional condition differing from the internal magnetic field; and wherein the evaluator is configured to evaluate the time curve together with the additional condition.
 14. The device as claimed in claim 13, wherein the provider is configured to provide an indication, by means of the additional condition, as to the side from which the movable object has approached the goal.
 15. The device as claimed in claim 14, wherein the provider is configured to detect force and/or motion ratios of the movable object.
 16. The device as claimed in claim 12, the provider being located within the movable object.
 17. The device as claimed in claim 16, the provider comprising a magnetic field sensor.
 18. The device as claimed in claim 17, the magnetic field sensor of the provider being a three-dimensional magnetic field sensor.
 19. The device as claimed in claim 16, the evaluator being, located within the movable object.
 20. The device as claimed in claim 16, wherein the evaluator is not located within the movable object, and wherein the provider may be coupled to the evaluator.
 21. The device as claimed in claim 20, the evaluator further comprising a receiver for receiving a sequence of magnetic-field measured values from the movable object.
 22. The device as claimed in claim 21, the receiver being a radio receiver.
 23. The device as claimed in claim 12, the evaluator being configured to provide the goal statement by means of a derivation of the time curve of the magnetic field with respect to time.
 24. The device as claimed in claim 23, wherein the derivation of the time curve of the magnetic field with respect to time d|B|/dt approximately equals zero at the moment the goal line is crossed.
 25. The device as claimed in claim 13, the additional condition of the evaluator being a Doppler frequency which occurs due to the movable object moving toward or away from the evaluator.
 26. The device as claimed in claim 12, the evaluator being configured to obtain the goal statement by comparing the measured values of the sequence of measured values with values determined in advance.
 28. A method for generating a magnetic field within a goal having a bounded goal area which is defined by the goal and through which a movable object is to be brought to achieve a goal, comprising a step of generating an internal magnetic field larger than an external magnetic field present outside the goal area.
 29. A method of determining whether a movable object has been brought through a goal having a goal area defined by the goal, an internal magnetic field being measurable, within the goal area or in parallel with the goal area, which is larger than an external magnetic field present outside the goal area, the method comprising: providing information about a magnetic field experienced by the movable object; and evaluating the information about the magnetic field to provide a goal statement by means of a detection that the movable object has passed through the internal magnetic field.
 30. A method for deciding whether a movable object has been brought through a goal having a goal area defined by the goal, an internal magnetic field being measurable, within the goal area or in parallel with the goal area, which is larger than an external magnetic field present outside the goal area, the method comprising: generating the internal magnetic field within the goal; providing information about a magnetic field experienced by the movable object; and evaluating the information about the magnetic field to provide a goal statement by means of a detection that the movable object has passed through the internal magnetic field.
 31. A computer program having a program code for performing the method for generating a magnetic field within a goal having a bounded goal area which is defined by the goal and through which a movable object is to be brought to achieve a goal, comprising a step of generating an internal magnetic field larger than an external magnetic field present outside the goal area, when the computer program runs on a computer or a microcontroller.
 32. A computer program having a program code for performing the method of determining whether a movable object has been brought through a goal having a goal area defined by the goal, an internal magnetic field being measurable, within the goal area or in parallel with the goal area, which is larger than an external magnetic field present outside the goal area, the method comprising: providing information about a magnetic field experienced by the movable object; and evaluating the information about the magnetic field to provide a goal statement by means of a detection that the movable object has passed through the internal magnetic field, when the computer program runs on a computer or a microcontroller.
 33. A computer program having a program code for performing the method for deciding whether a movable object has been brought through a goal having a goal area defined by the goal, an internal magnetic field being measurable, within the goal area or in parallel with the goal area, which is larger than an external magnetic field present outside the goal area, the method comprising: generating the internal magnetic field within the goal; providing information about a magnetic field experienced by the movable object; and evaluating the information about the magnetic field to provide a goal statement by means of detection that the movable object has passed through the internal magnetic field, when the computer program runs on a computer or a microcontroller. 